This issue mirrors the design of https://flutter.dev/go/material-theme-system-updates

Rename the TextTheme TextStyles

• Migrate TextTheme to 2018 APIs #48547
• Deprecate Material 2 text style properties #98746

Deprecate/remove the accent properties

• ☂️ Remove accentColor and accentTextTheme from ThemeData et al. #56918

Compute brightness, primaryColorBrightness, accentColorBrightness

• Deprecate accentColorBrightness Deprecate ThemeData accentColor, accentColorBright, accentIconTheme, accentTextTheme #81336
• Change ThemeData.brightness to be a simple getter that returns colorScheme.brightness ThemeData.brightness == ThemeData.colorScheme.brightness #56956
• Update SearchDelegate Updated SearchDelegate to follow custom InputDecorationTheme #55209
• Update GridTileBar Removed GridTileBar accentColor dependency. #78574
• Deprecate primaryColorBrightness Deprecate primaryColorBrightness #93396

Deprecate/move/remove the 21 grab-bag properties

(x) indicates number of references, excludingtheme_data.dart and tests. This can be used a proxy for disruptiveness/ease of deprecation.

• Deprecate ThemeData.canvasColor [ThemeData 🧹] Remove canvasColor usages #116350
• Deprecate ThemeData.scaffoldBackgroundColor [ThemeData 🧹] Remove scaffoldBackgroundColor usages #116341
• Deprecate ThemeData.cardColor [ThemeData 🧹] Remove cardColor usages #116349
• Deprecate ThemeData.dividerColor [ThemeData 🧹] Remove dividerColor usages #116347
• Deprecate ThemeData.secondaryHeaderColor [ThemeData 🧹] Remove secondaryHeaderColor usages #116342
• Deprecate ThemeData.hintColor [ThemeData 🧹] Remove hintColor usages #116346
• Deprecate ThemeData.splashColor (5) ⇒ inkColor or inkFeatureColor
• Deprecate ThemeData.unselectedWidgetColor (11) ⇒ see toggleableActiveColor deprecation
• Deprecate ThemeData.bottomAppBarColor ⇒ Deprecate ThemeData.bottomAppBarColor #111080
• Deprecate ThemeData.selectedRowColor Deprecate ThemeData.selectedRowColor #109070
• Deprecate ThemeData.buttonColor Deprecated ThemeData buttonColor #82196
• Deprecate ThemeData.textSelectionColor TextSelectionTheme support (step 3 of 3) #66482
• Deprecate ThemeData.cursorColor TextSelectionTheme support (step 3 of 3) #66482
• Deprecate ThemeData.textSelectionHandleColor TextSelectionTheme support (step 3 of 3) #66482
• Deprecate ThemeData.backgroundColor Deprecate ThemeData errorColor and backgroundColor #110162
• Deprecate ThemeData.dialogBackgroundColor Deprecate ThemeData.dialogBackgroundColor in favor of DialogThemeData.backgroundColor #155072
• Deprecate ThemeData.indicatorColor Deprecate ThemeData.indicatorColor in favor of TabBarThemeData.indicatorColor #160024
• Deprecate ThemeData.errorColor Deprecate ThemeData errorColor and backgroundColor #110162
• Deprecate ThemeData.toggleableActiveColor Deprecate toggleableActiveColor #97972

Additional grab-bag properties

These grab-bag properties not in the original linked proposal, but can also be deprecated:

• Deprecate ThemeData.shadowColor [ThemeData 🧹] Remove shadowColor usages #116343
• Deprecate ThemeData.splashFactory (4) ⇒ inkFactory or inkFeatureFactory
• Deprecate primaryColor Deprecate ThemeData.primaryX #110848
• Deprecate primaryColorDark [ThemeData 🧹] Remove primaryColorLight & primaryColorDark usages #116362
• Deprecate primaryColorLight [ThemeData 🧹] Remove primaryColorLight & primaryColorDark usages #116362
• Deprecate ThemeData.fixTextFieldOutlineLabel Deprecate ThemeData.fixTextFieldOutlineLabel #87281

These factory constructor parameters can also be deprecated:

• Deprecate primarySwatch from ThemeData factory constructor (8) ⇒ colorScheme or colorSchemeSeedColor (related Deprecate ColorScheme.fromSwatch #120064)

Property colors not subject to removal

• State colors like ThemeData.disabledColor (26), ThemeData.focusColor (19), and ThemeData.hoverColor (19) have high usage and are shared amongst many components
• There is similar widespread usage for ThemeData.highlightColor (13)
• Other parameters can remain in the factory constructor (e.g. ThemeData.fontFamily and ThemeData.fontFamilyFallback) for convenience

Component Theme Normalization

All of the existing themes have been normalized except for the following:

• AppBarTheme Normalize AppBarTheme #169130
• BottomAppBarTheme Normalize BottomAppBarTheme #168586
• InputDecorationTheme Normalize input decoration theme #168981
• CardTheme Normalize Card theme #151914
• ChipTheme Reland "ChipThemeData is now conventional" #94179
• DialogThemeNormalize Dialog theme #153982
• ListTileTheme Reland Refactored ListTileTheme: ListTileThemeData, ThemeData.listThemeData #91840
• TabBarTheme Normalize TabBarTheme #155476